GILLMAN, Franz:Gesammelte Schriften zur klassischen Kanonistik. Schriften zum Dekret Gratians und zu den Dekretisten, Echter, Würzburg 1988.
MIRAMON, Charles:Innocent III, Huguccio de Ferrare et Hubert de Pirovano: Droit canonique, théologie et philosophie à Bologne dans les années 1180, in: MÜLLER, Wolfgang/SOMMAR, Mary (ed.):Medieval Church Law and the Origins of the Western Legal Tradition. A Tribute to Kenneth Pennington, Catholic University of America Press 2006, p.320-346.
MÜLLER, Wolfgang:Huguccio: the life, works, and thought of a twelfth-century jurist, in:Studies in Medieval and Early Modern Canon Law, Vol. 3, Catholic University of America Press, Washington 1994. (Table of Content)